Creatinine Clearance Formula CockroftMDRD Sex M F Age (years) Weight (kg) Serum Creatinine (mcMol/L) Race OtherAfro-american Creatinine Clearance mL/min Result is valid only for a stable Serum Creatinine. MDRD : result not accurate for clearance >60. MDRD : to be used for CRF only. Drug dosage adaptation : prefer Cockroft.